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Yes, the overall design of the machine is very good, but there are a few areas that need attention.I didn't use washer/shims to correct mine, I used the bending trick I mentioned (with a 5/16 drill bit) and it worked out well. You can dial in precisely how much to bend the sheet metal (although it is very subtle) and it felt like the end mount was plenty strong to take the load. The only drawback when using washers, is you are going to need a collection of washers with varying thicknesses in order to pick the right amount of shimming.

Regarding the glass option, I used a 3mm borosilicate glass, which is relatively thick and very strong (also heat resistant), so it really didn't change shape much after being clamped (my bed was also slightly domed up). Additionally, if you use the silicon thermal pad underneath, it is soft enough to compensate for the uneven aluminum.

Also, you should assess flatness with a good straight edge and not rely on the hot end clearance with the bed. As you see from my post, the bed appeared to be .2mm high in the center when checking clearance with the hot end, but measured perfectly flat using a straight edge. The bowed rods was deceiving you into thinking the bed was warped when in fact it was the shift in travel as the bed moved along the rods.